Food cooking device



Jan. 14-, 1947.

R. SARDESON 2,414,396

FOOD COOKING DEVICE Filed April 17, 1942 3 Sheets-Sheet l INSULATI N Robert r&eser

Patented Jan. 14, 1947 FOOD CGOKING DEVICE Robert Sardeson, Minneapolis, Minn., assignor to Harold C. Genter, Minneapolis, Minn.

Application April 17, 1942, Serial No. 439,346

8 Claims. 1

My invention relates to cooking devices and particularly to electrically operated bread toasters.

, An object of the invention resides in providing a cooking device adapted to be automatically compensated for variations of the voltage of the electric current used for operating the same.

Another object of the invention resides in providing a periodically operable cooking device having a timing mechanism for terminating the cooking operation and including a thermally responsive member and an electrical heater therefor and in further providing means dependent upon variations in voltage of the source of current for varying the period of the timing mechanism.

An object of the invention resides in providing a food cooking device including a resistor having a high temperature coeflicient of resistance adapted to be energized by the same source of electric current as the food cooking device and operating to vary the timing period of the cooking device.

A feature of the invention resides in providing a main heating circuit having the heating means therein and in connecting the thermally variable resistor in the main circuit in series with the heating means.

A still further object of the invention resides in connecting the heating means, heater and resistor in series in the main heating circuit.

Another object of the invention resides in providing a by-pass circuit with a resistance having a low temperature coefficient of resistance shunting said resistor.

An object of the invention resides in providing a food cooking device in which the cooking continues without interruption until th cooking operation is completed.

A still further object of the invention resides in providing a cooking device in which the heating means and resistor are continuously energized during the cooking period.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

In the drawings:

Fig. 1 is an elevational sectional View of a bread toaster illustrating an embodiment of my invention.

Fig. 2 is an elevational sectional view taken on line 2-2 of Fig. 1.

Fig. 3 is a view similar to Fig. 2 taken on line 3-3 of Fig. 1.-

a center.

Fig. 4 is a fragmentary inverted view of the invention with arts removed.

Fig. 5 is a wiring diagram of the invention.

In the use of electrically operated toasters, it has been found in certain types of toasters that, when the voltage drops, the color of the toast produced becomes considerably darker, and when the voltage rises, the toast becomes too light in color. The present invention provides a construction in which uniform results are produced regardless of the voltage of the electric current.

For the purpose of illustrating my invention, I have shown in the drawings at A a bread toaster such as illustrated in my co-pending application e for patent Serial No. 289,905, filed August 12,

1939. This toaster has the inherent characteristic that, when the voltage drops, the color of the toast becomes darker. This toaster will now be described in detail.

The toaster A consists of a frame l0, best shown in Fig. 1. This frame carries Within itself a toaster l I, and exteriorly thereof a timing mechanism 12 for controlling the timed operation of the toaster. In conjunction therewith compensating means, indicated in its entirety by the reference numeral l 3 is employed which serves to control the operation of the toaster to procure uniform toasting under varying voltage of the source of electrical energy.

The frame 10 consists of a lower horizontal frame member I4 constructed from sheet metal and two vertical end frame members l5 and I6 extending upwardly from the frame member M. The frame further includes an upper horizontal frame member I? which connects the two frame members I 5 and i6 together at their upper ends. The upper frame member I! is provided with downwardly turned flanges l8 which are secured to the end frame members l5 and 16 by means of bolts IS.

The frame is supported on a base 2|, best shown in Fig. 1, which is constructed from a suitable molded material and extends about the outer confines of the toaster, being open at the This base is constructed with a circumferentially extending rabbet 22 therein in which portions of the toaster frame member l4 rest. The frame I0 is held attached to the base 2| by means of screws 23 which are threaded in the frame member l4 and pass through cars 24 formed on the base H. The base 2| is constructed with feet 25 which raise the base above the surface on which the toaster rests and provides spaces 26 therebetween for the admission of air into the toaster proper.

V openings 38.

framemember ii, the same is formed with down- The toaster H is constructed in the following manner: Disposed between the two upper and lower frame members i l and I! are four heating elements 2? which are arranged in spaced relation to provide two bread ovens or toasting chambers 28 and 29 therebetween. Each of these heating elements is constructed from two sets of a suit- I able heat resisting insulating material 32 on which are wound coils 3| constructed of resistance wire or ribbon. The two sheets of insulating material 32 of each heating element are connected together by means of connectors 30.

which overlie the same and are riveted thereto. The heating elements 2? are secured together through threaded spindles 33 which pass through the various sheets of insulating material 32. Nuts 36 threaded upon the spindles support the sheets of insulating material in spaced relation to form the toasting chambers :28 and 29. The various heating elements 2i rest directly upon the lower frame member ii-of frame I9 and are held in position thereon by-means of lugs 34 which are struck-upfromthelower frame member I l.

, The frame member [4 is formed with openings 35 therein which are. so constructed as to provide lugs- 3? extending inwardly into the same. The upper frame member ll is similarly constructed andis formed with two longitudinally extending At the marginal portions of the wardly turned flanges39which engage the outermost of the heating elements 21. Lugs 4|, struck out of theframe member l'l, further engage the heating elements and hold said heating elements inproper position at their upper ends.

The. bread ovens 28 and 29 are provided with a number of. guard wires 42 which extend through the upper frame member I1. and through the lugs 31* ofthe lower frame member I4 These wire. guards hold the bread in proper position centralized between the pairsof heating elements 2.1 for eachbread oven.

Disposed within each bread oven 28 and 29 and movable. between the sets ofguard wires 42 is a bread rack 43. bar. 44' of sheet metal which is constructed at the endsthereof with ears 451' and dewhich are bent at right angles to the same and which project through vertical slots ET and 48 formed in. the end frame members I5 and 16.

The bread racks 43' are supported by a carriage 69, best shown in Figs. 2' and 3. This carriage consists of a plate 'H'having a flange i2 turned outwardly therefrom. Attached to this flange are two arms 13" formed with lugs is bent out- I wardly therefrom and parallel with the slots 4? and E8. Theears 46 0f the bread racks 43 project beyond the end frame member l6 and. are secured to the lugs I l by means of screws 15. In this manner. the two bread racks are supported on the carriage 69 and are adapted to move vertically along'the slots 57 and 48 through guidance of "said carriage.

The carriage 69'is guided for vertical movement'in' the following manner: Attachedto the end frame member It of frame 59 is a support 16. This supportis constructed from sheet metal and is formed to .provide two spaced uprights T1 and-18'; These uprights are spaced to provide a slot 891 therebetween extending throughout said support. The lowermost portion of. the support l fi is'formed with an attaching lug 79 which is bent outwardly therefrom and which is attached This bread rack consists of a to the end frame'member l6 by means of a screw 8!. The upper ends of' the uprights Ti member ll.

bracket 82 which projects outwardly from and is integral with the flange is of the upper frame This bracket is apertured to receive the ends of said uprights and hold the same in proper relation to one another and to the frame 9. The carriage 69 is provided with two grooved rollers 83 which engage the edges of the uprights Tu and is at the slot 88 and which are pivoted on pintles 84% attached to said carriage. By means of this construction, the carriage is guided for vertical movement and the two bread racks G3 are supported and correspondingly guided'for movement within the bread ovens 28 and 29.

The carriage 69, as best shown in Fig. 2, has a lug 85 projecting outwardly therefrom. One end of a tension coil spring 86 is hooked on the lug 85 and the other end of said spring is hooked on another lug 81 formed on the bracket 82. This spring provid'es the energy for raising the carriage 6'9 and the two bread racks it when the toasting operation is completed, and also provides energy for actuating the timing mechanism [2; as will be presently more fully described.

The entire toaster H and the timing mechanism l2are'ienclosed'by means ofa case 9!. This case has lateral walls 92 and a top 93 connected therewith and is'open atithebottom. The lower ends of the lateral walls 92 rest in the rabbet 22 of the base 2T. Issuing inwardly from the end walls of said case are cars 96- which are threaded torec'eive screws 95: These screws pass through ears eflwhich are formed on the base 2| and underlie the ears 94. The top 93' of case 9| is constructed with two longitudinally extending openings 96" which are directly disposed above the-bread ovens 28 and Hand which guide slices of bread into the bread ovens between sets of guard wires 42 In initiating operation of the toaster, the carriage 69' ismoved to its lowermost position by means of an arm 88, best shown in Fig. 1. This armprojects outwardly-through a slot 91 in the end wall of case 9| and has attached to its outer end a finger piece'98 by means of which the said arm may be depressed. When pressure is applied to the said finger piece, carriage 69 is lowered against theaction of spring 86 and the breaduracks 43' brought into toasting position. The case. 9i is also provided at its opposite end wall with a stationary finger piece 99, similar to the finger piece 98, which finger pieces may be used for carrying the toasterabout.

The timing mechanism l2 of my invention consists of a strip of bi-metal i ii 5, shown in Figs. 1 3 and 4, which is movable in the direction of its length and is guidedfor movement in the following manner: Issuing outwardly from the upright H of support [6 is'a flange I 92. This flange has secured to the lowermost end thereof aguide I03" which is attached to said flange through-screws IM. This guide has a central opening IBE through which the bi-metal extends and is provided with ears liifi extending into said opening to restrain movement of the bi-metal outof the same;. A button Hi1, formed on the guide l93 serves as a support for the bi-metal throughout its travel along the said guide. The strip. of bi-metal ifll is further'guided for movement in a similar guide I98 which is pivoted to the flange l02- of supportlG. For this purpose, the said guide is constructed with; two'ears I09 which are journaled on a stub shaft H0 fast on thef lang'e I92. A tension spring III is hooked atone end to a finger H2 on the guide I98 and at its other end on a pin I I 3 secured to the flange I02. This spring holds the guide I98 in its lowermost position, as shown in Fig. 3.

The strip of bi-metal IIII is constructed with a series of openings H4 arranged in spaced relation throughout the length thereof. These openings leave intervening portions H5 which form a rack indicated in its entiret by the reference numeral H6. Cooperating with the rack H6 is a segment of a pinion III which has teeth H8 adapted to mesh with the openings H4 of rack H6. This pinion segment is attached to a shaft H9 which is journaled in a bearing I 2I secured to the flange I92. By means of this construction, the pinion segment I I I may rotate with relation to the rack H6, thereby controlling the movement of said rack. The pinion segment III has attached to it a small section I22 of a ratchet wheel, which is provided with ratchet teeth I23. This ratchet section is spaced from the pinion II! and is secured thereto in concentric relation with reference to the teeth I It by means of rivets I24. Pivoted on a stud I23 issuing outwardly from the flange I92 of support I6 is a detent I26 which has a catch I2? adapted to engage the various teeth I23 of the ratchet section I22. The detent I26 i provided with a finger I 28 which rides along the upper surface of the strip of bimetal I9I and to one side of the row of openings I I4 therein. Finger I 23 is held in engagement with the strip of bi-rnetal, by means of a tension coil spring I33 which is attached at one end to detent I26 and at its other end to a pin I49 issuing outwardly from the flange I62 of support I6. When the bi-metal bows upwardly, finger I28 is raised and the catch I2? of detent is disengaged from the particular tooth I23 of ratchet section I22 with which the same was engaged. Rotation of the pinion segment I IT in a clockwise direction is procured by means of a tension coil spring I29 which is hooked at one end to the bracket 82 and at its other end to a pin I3I issuing outwardly from the pinion III. By means of this spring, movement of the strip of bi-metal I III toward the left is procured, as shown in Fig. 3, when the detent I26 is successively disengaged from the ratchet teeth I23.

Operation of the detent I26 is caused by the heating of the strip of bi-metal IIII at a locality between the two guides I93 and I38. For this purpose, a hairpin heater I 32 is employed which is attached to an insulating mounting I33, by means of two screws I34 and I35. The mounting I33 is attached to a lug I36 bent outwardly from the flange I92 of support I6 by means of screws I31. The mounting I33 is disposed outwardly of the said flange, as best shown in Figs. 2 and 4.

The carriage 69 is latched in its lowermost position by means of a latch I38, This latch is pivoted on a stud I50 secured to flange I62 of support I6. Said latch has a catch I39 which is adapted to engage a latch lug I4I attached to the carriage 69. The said latch I38 is constructed with a finger I32 which engages bearing I2I and limits movement of the catch I39 into latching position. A tension coil spring I43 secured at one end to the finger I42 and at its other end to a spring support I43, carried by the flange I92 urges the latch I38 into latching position. Mounted on the pinion segment III is a pin I45. When the last tooth of the teeth I32 of the ratchet section I22 has been released by the detent I26, spring I29 causes continued rotation of 6 the pinion segment II! and urges the pin I45 into engagement with the finger I42 of latch I38. This disengages the catch I39 from the latch lug MI and frees the carriage which is raised to its uppermost position through the action of the spring 66.

For returning the pinion segment II! to normal position, a cam I46 is employed which is pivoted on the shaft H9. This cam has a shoulder it! which is adapted to engage the pin I45 on the pinion segment H1, The said cam also has a cam surface I48 which is adapted to be engaged by a roller I49, rotatably mounted on a stud I6I secured to a lug I52 issuing outwardly from the carriage 63. As the carriage 69 travels upwardly,

said roller engages cam surface I48 and brings the shoulder I 4! into engagement with pin I45, moving the pinion segment III in a counterclockwise direction.

For controlling the energization of the heating elements 21, a switch, indicated in its entirety by the reference numeral I53, is employed. This switch utilizes the screw I34 holding heater I32 in place which screw is constructed with a contact head I64. A leaf spring switch arm IE5 is attached to an insulating support I56 by means of a screw I51. This support, as best shown in Fig. 2, issues outwardly from and is made as a part of the base 2!. The arm I55 has a contact I58 which is adapted to engage the contact I54. The end of the arm I55 is bent back to form an engaging portion I59 adapted to be engaged by an insulating button 26Igattached to a bracket extending outwardly from the carriage 69. When the carriage 69 is lowered, button 26! engages the engaging portion I59 of arm I55 and brings contact I58 into engagement with the contact I54 thereby closing the circuit through the switch I53.

Variations in the brownness of the toast toasted by the invention is procured by moving the movable guide I98 for the strip of bi-metal IOI in a manner to raise and lower the right hand portion of th bi-rnetal, as viewed in Figs. 3 and 2. This varies the amount of engagement of catch I2! of detent I26 with the teeth I23 of the ratchet section I22. It will readily be comprehended that, when this portion of the bi-metal is raised, less arching of the bi-metal will be necessary to disengage catch I2! from the tooth I23 with which it was engaged, thereby reducing the length of time necessary to release the detent from each tooth of the ratchet section I22 and vice versa. As shown in Fig. 2, the guide I98 is constructed with an arm I19 projecting outwardly therefrom. This arm has screwed in it an adjusting screw IBI which is adapted to engage the surface of a cam I82. Cam I82 is secured to a shaft I89 which projects outwardly through the case and has attached to it a knob I83 by means of which the same may be rotated. Shaft I88 is journaled for rotation in a hole drilled in the flange I02. Friction is aiforded between the cam I82 and the flange I92 through a spring I85 which overlies the outer surface of said cam. This spring has an abutment I86 at its upper end which engages the flange I92, A rivet I81 passing through said spring and the flange I92 urges the lowermost end of the said spring into engagement with cam I82 and effects the desired result.

Manual release of the bread carriage 69 may be accomplished in the following manner: Pivoted to a lug I88 on flang III-2 through a rivet I89 is a lever I9I. This lever has a finger I92 extending at their ends.

through the case 3|. A button I33, attached to the end-of this finger permits'ofpressing thefinxger inwardly. Lever-I! isformed with'an arm lfifirextending through the flange I02-of support i6, which arm is adapted to engage the arm I10. When the button I93 is pressed inwardly, lever .I QI is oscillated to depress arm II9. This raises the bi-metal guide I08 sufiiciently to move the detent I26 out of engagement with the teeth I23 of ratchet section M32. The bi-metal' is then permitted to travel from right to left, movement thereof being procured through the spring 129.

7 When the pin I05, on thepinion segment II'I-engages the finger I02 of latch I33, the bread car- .riage'66 isreleased and the bread racks 43 move .totheir uppermost position.

In order to cushion the action of the bread carriagein raising to its uppermost position, a dash pot I60 is employed. This dashpot comprises a cylinder I6! which is mounted on a mounting I62, secured to the flange I02 of support I6. Said dash pot further includes a piston I95 which has "by means of screws III]. This plate has a flange I6! extending upwardly therefrom which is adapted-to overlie the vertical frame member 16 of the frame I0. In the plate I65 are formed various openings I66 which control the entry of air into the portion of the case 9| in which the timing mechanism is disposed. The air entering this, portion of the case escapes through openings I68 in the end frame member I6 and passes outwardly from the case 6| through the openings 36 in the top 63 thereof. The heater I32 is completely enclosed about the sides and from beneath the same by. means of a housing I69 which is secured to the plate I65.

For the purpose of collecting the bread crumbs from the bread deposited in the toast ovens 28 and 26, a crumb pan Iii is employed which is disposed beneath the frame I0 and which is attached to the base 2! by means of studs I12 screwed to the lower frame member I6, and nuts I13 screwed upon th lower threaded ends of the same.

The compensating means I3 of the invention includes a resistor or resistance 200 which is con- .structed of a metal having the characteristic that the resistance of the same increases very rapidly with increase of temperature thereof. One such metal is iron, which to a marked degree increases in resistance upon increase in temperature. Another material which serves the purpose is an alloy consisting of approximately 70% of nickel and 30% of iron. The resistor 200 is constructed of wire and is wound to form two open coils 200 and 200* The wire is suiiiciently heavy so that the coils become self-supporting when attached Attached to the plate I6 of frame I0 nearthe lowermost portion thereof are four binding posts 203, 206, 2 I6 and 2II which are insulatedirom the said plate I6. The binding posts 2-03'and 206 are disposed on'one-side of the plate and'the'binding posts ZI-B and 211 on the other .fr-ame I0 of the-toaster and are situated above the plate 65. The two coils 200 and 200 are connected in series Icy-means of a conductor 2I8 whichis connected to the two binding posts 206 and 2H5. In addition to the resistor 200, a resitsance 20 is employed which has a relatively low temperature coeificient of resistance, as compared to thatof the resistor 260. A material such asthat used for-the heatingcoils 3I whichconsists of an alloy comprising approximately nickel and 26% chromium is suitable. The resistance 20.4 is also constructed of sufiiciently heavy wireso that the same may be formed in an open coil which is disposed on the opposite side of the end plate I6 from that on which the vresistor 200 is disposed. The resistance 204 is arranged vertically, one end thereof being connected under the binding post 203 and the other end thereof being connected under another binding post 205 also attached to the end plate I6 and insulated therefrom. Resistance 2% is mounted on the same side of the frame member I6 as is the bread oven, so that the heat given ofi by resistance 204 does not cause overheating of the moving parts which constitute the timing mechanism. Suitable openings 2L3 in the plate I65 provide sufi'icient draft for cooling the resistor 200 the desired amount.

In Fig. 5, which is a Wiring diagram of the invention, the heating elements 2'! are all shown as connected in parallel to two conductors 207 and 200. The conductor 20? is connected to one side of a line 209-2I0 for supplying electrical energy to the toaster. The resistor 200 is connected by means of a conductor 2 with the conductor 208, andis further connected by a conductor 2H, with th heater I32. Heater I32 is connected by means of a conductor 2I3 to the switch I53, which, in turn, is connected to the other side 2I0 of the line. This forms the main circuit of the toaster. The resistance 204 is connected by means of a conductor 2 I4 to conductor 2 and is further connected by means of a conductor '2I5 to the conductor 2I3. It will become evident that the resistor 200 and heater I32 are connected in series and that the resistance 204 shunts the circuit containing the said heater and resistor, thus forming a by-pass about the same. It will be further noted that the said heater, resistor and resistance are connected as a unit in series with the heating elements 21 which form the'hcating means of the toaster and which elements are themselves connected in multiple.

I have found that, where the toaster draws approximately 1100 watts, the resistor 200 would operate satisfactorily, if constructed of iron wire, with a diameter of .020 inch and a length of approximately 12 inches. To cooperate with a resistor of such dimensions, the resistance 204, if constructed of nickel-chromium wire, would have a diameter of .032 inch and a length suflicient to give 1.5 ohms resistance. If the alloy, previously referred to, were used for resistor 200, a wire having a diameter of .028 inch and a length of 20 inches would be used. In the toaster above described, the heater I32 is preferably constructed of nickel-chromium sheet material which is stamped as shown in Fig. 4. This 9 I heatermay be constructed of sheet material of a thickness .0035 inch and of a suitable length to give a resistance of .55 ohm.

Applicant has found that the values above designated operate satisfactorily to produce uniform toasting in a device of the character described Within the limits of 100 to 120 volts. While theabove noted values have been found satisfactory it can also be readily comprehended that the same may be varied within reasonable limits and satisfactory results procured.

The operation of my invention is as follows: With a toaster constructed in accordance with my application for patent above referred to, increase in line voltage produces an excessive decrease in the timing period and a corresponding decrease of brownness of the toast with the same adjustment of the toaster. This may best be explained as follows: The increase in energy consumed by the heater I32 varies as the square of the voltage while the losses due to radiation of heat from the heater remain fairly constant, the heater being thermally isolated from the heating means of the toaster used for toasting the bread by means of housing I69. Thus the percentage of increase in heat transmitted by the heater I32 to the bi-metal H6 is far in excess of the percentage of rise in voltage and the timing mechanism 12 which depends for operation upon the heat imparted to the bi-metal H6 operates more rapidly and the timing cycle is reduced beyond that necessary to compensate for the added energy supplied to the heating means 3|. An increasein the voltage across the line 239'2I0 in the instant invention would cause a corresponding increase across the resistor 230 and the heater I32. This would likewise cause an increase in voltage across the resistance 204. The ratio between the resistance of the resistor 203 and resistance 204 would,

however, be disturbed since the specific'resistance of the resistor 200 increases upon increase in temperature. Such increase-in the resistance. of the resistor 20!] would change the proportion of the current flowing through the said resistor and resistance 234, so that, upon increase in voltage, the percentage of increase of the current through the resistor 200 becomes less. At the same time, the rate of change of current through the heater I32 becomes less, it being connectedin series with resistor 230, so that variationin current through this heater does not vary as would be the case with the resistor 200 omitted, but becomesle ss. This has the effect of reducing the maximum temperature of the heater I32, so that it takes longer to heat up the strip of bi-metal IOI. Accordingly, the timing period is increased and compensation for the excessive decrease in timing period produced by high voltage is procured.

In actual tests on a toaster constructed in accordance with my invention, the following measurements were taken. With a line voltage of 100 volts, the voltage drop across the resistance 204 was 5.7 volts, and across the resistor 200 and the heater I32 were 2.6 volts and 3.1 volts, respectively. Upon a 10% increase in the line voltage, the drop across-the resistance 294 became 6.7 volts, showing an increase of I'l /2%. This increase in percentage of voltage drop is due to the increase in specific resistance of the resistor 260. This voltage drop divided itself between the resistor 200 and the heater I32 in proportion to their resistances which gave a voltage drop of 3.45 volts across resistor 200, and 3.25 volts across heater I32.

It will thus be readily comprehended that the drop across heater I32 at 110 volts is greater than the drop across the resistor 200 at the same voltage, whereas the reverse was true at a line voltage of volts. This represents an increase of .15 volt over the original voltage drop of 3.1 volts of heater I32, which amounts to 4.8%, as contrasted to the 10% increase in line voltage. When the line voltage was increased 20%, the drop across the resistor 204 measured 7.7 volts, which drop became divided between the resistor 290 and the heater I32 in the proportion 4.35 volts and 3.35 volts. This represents an increase of .25 volt over the original 3.1 volts across the heater I32 resulting in an 8% increase in line voltage. The result is that the disadvantages of the structure shown in my copending application for patent may be corrected by selecting the proper values of the resistances of the resistor 200 and the resistance 204, so that uniform brownness of toast can be procured for all voltages within feasible limits. It will thus be readily comprehended that the rate of increase of current through heater I32 is not proportional to the rate of increase of the line voltage but decreases sufiiciently to permit of compensating for the excessive reduction in the rate of decrease of the timing period produced by increasing voltage.

The advantages of my invention are manifest. My improved toaster is fully automatic and automatically compensates for variations in voltage. My invention does not require any moving parts for procuring compensation and is not subject to Wear or deterioration. The compensating feature of my invention may be incorporated in the toaster proper at a nominal expense. For any particular kind of bread, duplications of the brownness of the toast may be procured without re-adjustment of the toaster regardless of voltage. 7

Changes in the specific form of my invention, as herein disclosed, may be made within the scope of what is claimed without departing from the spirit of my invention.

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In a periodically operated cooking device, electrical heating means, a timing mechanism including a thermally responsive member, an electric heater therefor, a circuit for connection to a source of electrical energy, a resistor having a high temperature co-efiicient of resistance as compared to that of the heating means, said heating means, heater and resistor being connected in series in said circuit, means operated by said thermally responsive member for deenergizing said heating means and heater to terminate the cooking period, a resistance shunting said resistor and heater and having a temperature coefficient differing from that of said resistor, said heating means, resistor, heater and resistance being all energized continuously during the cooking cycle, said resistor operating upon variation of the voltage of the source of electrical energy to vary the proportion of the current through said resistance and through said heater, thereby varying the timing period to procure uniform toastingregardless of variation in voltage.

2. In a periodically operated cooking device, electrical heating means, a timing mechanism including a thermally responsive member, an electric heater therefor, a main circuit for connection to a source of electrical energy, a resistor having a high temperature coefficient of resistance as compared to that of the heating means,

said heating means, heater and resistor being connectedin series'in said main circuit, aby pass circuit by-passing said heater and resistor, a resistance in said Joy-pass circuit, said heating means, heater, resistor and'resistance being all energized continuously during thecooking cycle, means operated by said thermally responsive member for deenergizing said; heating. means and heater; to terminate the, cooking period, said resistoroperating upon,- variation of the voltage-of the sourceofelectrical energy to vary the'proportion of}v the current through said resistance and throughsaidheater thereby varying the timing period to procure uniform toasting regardlessof variation in voltage.

V 3; In a periodically operated: cooking, device, electrical heatingimeans; atiming, mechanism including; a thermally responsive member; an. electric heatentherefor, a circuit for, connection toa source, of electrical-energy, a resistor having a high temperature coeificient of resistance as compared to that of the heating, means, said heating means, heater and resistor beingconnected in seriesin said circuit, aresistance shunting said resistor and-heater and-having-a' temperature coeificient difiering from that of: said resistor, said heating means, resistor, heater and resistance being all energized continuously during the. cocking. cycle, means operated by said thermally responsive member fordeenergizing said heating 5 mium material having a resistance of HIPFIOXi-y mately .55 ohms, a circuit for connection to: a

source: or electrical energy having a voltage of between, 100 volts:-and; l20 volts, a resiston constructed of a length of wireoff about .028 inches inidiam'eter and about 20 inches long and: formed ofialmaterial composed; of about:;70:% nickeland 30% iron, said heatingmeans, resistor-and :heater being-connected:Lin:.series;in said circuit; means operatedybysaid thermally responsivemember for-deenergizing said heating: means and heater toyterminatethe.cookingrperiod, aresistance constructed Jof;a,;length;of .nickelchromium wire-of a diameter of: about .032- inches; and having a. re-

sistance of about 1:5 ohms-and shunting said-resistor, andtheater, said: heating, means, resistor,

heater: and: resistance all being energized tinuously during the cooking cycle; 1

5: In a; periodically operated cooking device, electrical heating means, a timing mechanism including ,a thermally responsive member, an electricheater therefor; a-circuit'for connection to a source: or electrical: energy, a' resistor-haying a 7 high: temperatureicoefiicient of resistance ascomparechtorthat cf, the heating means, said-heating means; heater-land: resistor: being connected in seriesfir'r saidicircuit; means operatediby saicl thermally responsive memberfor deenerg izing said heatingmeans, and. heater to. terminate the cooking :perio d, agresistance shunting said resistor Ell c 12 and heater and havinga temperature coefficient differing from thatof saidrresistor; said heating means, resiston heater and=resistancebeingall energized continuously during the cooking cycle, said resistor and resistancehavingvalues-such that the'rate of increase of currentthroughsaid heaterdi-fiers from. the I rate of increase ofthe voltageat the source.

6. Ina periodically operated cooking device,

' electrical heating -means,-a-.timing mechanism inof the source of electricalenergy to vary the-proportion of the current flowing through saidlresistance and throughsaid heater, therebyvarying the timing period, to "procureunif0rm toasting regardless of variation in voltage:

7, In a. periodically operated cooking device, electrical heating means; attiming mechanism including a thermallyresponsive' member, an'electric' heater therefor, a circuit for'connection to a source ofelectrical'energy; a resistance, said heating means, heaten and-resistancebeingconnected in series in said circuit, meansoperatedby said thermally; responsive: member for terminating thecookingperiod, a second resistance shunting said first resistance. and. heater, one, of-said resistances having ahigh temperatureacoefiicient of resistance as comparedto the otherresistance and operating uponrvariation" in voltage to. vary the; proportion of thecurrent flowing through the heater and through the second resistance. to vary. the timing period thereby varying; the timing period to procure uniform toastingregardless ofvariation in voltage. V

8.- In a periodically operated.- cooking device, electrical heatingv means, astimingmechanism includinga thermally responsive member, 3.1116120, tric heater. therefor, atcircuit for;connectiorrto a source of electrical energy, a resistance,- said heating means, heater and resistance being con.- nected in, series in said-circuit; meansoperatedzby said thermally responsive member. for terminating-the cooking period; a second resistance shunting said first resistance and heater, said: resistances. being energized, continuously during the energization of said-heater, onerof said resistanceshaving a high temperature-coeflicientof resistance as compared to the other resistance and: operating upon variation, in "voltagertoz varythe" proportion of; the current. flowing through the heater-and through the-second resistance-to vary the timingperiodi thereby;varyingethestiming period to procure uniform toasting;regardlessiof variationinvoltage. j V

ROBER'IfSA-RDESON: 

